The present invention relates to a wet type electro-photographic recording apparatus and, particulally, to a wet type electro-photographic recording apparatus by which both a proof sheet and a planographic sheet can be obtained.
As the so-called "total printing system" by which a print is obtained through the steps of picking-up an image, editing, correcting, preparing block copy, preparing stencil and printing, the following system is known:
(1) A color photographic film bearing an original information is color-decomposed to obtain a plurality of colors necessary for a process printing by means of an image pick-up portion such as image scanner or drum scanner.
Then, a color separation film having a dot-image is prepared for each color and a plate is prepared on the basis of the color separation film and corrected.
Colors used for a process printing includes usually subtractive primaries, that is, yellow (Y), magenta (M) and cyan (C), and black (BL).
When a proof sheet prepared is not acceptable, the color separation films are corrected, retouched, edited and/or patched, etc., manually. The color separation films thus corrected are returned to the image pick-up portion as a secondary original information. This process is repeated until the proof sheet becomes acceptable.
When the proof sheet is acceptable, a final planographic sheet for printing is prepared on the basis of the color separation films. An actual printing is performed with using a stencil of the planographic sheet thus prepared.
(2) A color photographic film bearing an original information is color-decomposed to obtain a plurality of colors necessary for a process printing by means of an image pick-up portion such as image scanner or drum scanner, as in the same manner used in the system (1) mentioned above.
Then, digital image data obtained from the image pick-up portion correspondingly to dot-images of the respective colors are stored in a storage (MT or hard disk, etc.) of a work station.
In this work station, an image processing such as layout, color regulation and edition, etc., are performed by using the digital image data stored in the storage.
A result of this image processing is displayed on a display screen or output from a digital color printer and checked on the display screen or the output image. When it is acceptable, color separation films for a block copy are prepared by means of a photographic film output device or a recorder portion of a drum scanner, etc., for correction.
A final planographic sheet for printing is prepared on the basis of the color separation films thus corrected and a proof sheet is prepared.
When the proof sheet is not acceptable, it is informed to the work station to repeat the above processing.
When the proof sheet is acceptable, a final planographic sheet for printing is prepared on the basis of the color separation films.
An actual printing is performed with using a stencil of the planographic sheet thus prepared.
The conventional printing systems mentioned above are based on color separation films for correction and preparation of stencil, respectively.
It is known, however, that formation of color separation films takes considerably long time and requires considerable manual procedures.
Further, there are many problems in storing and managing color separation films. Further, the process of correction based on the color separation films is not easy and requires skilled persons.
In addition to these problems, these conventional systems require very expensive correcting machines and plate making machines.
Japanese Patent Application Laid-open No. H3-9888 discloses a printing system which has no such problems as mentioned above.
The disclosed system includes an image pick-up portion for separating color of an original image information into a plurality of colors necessary for a process printing and a storage of a work station for storing digital image data corresponding to images of respective colors or digital image data output correspondingly to dot-images of respective colors.
In the work station, a user performs image processing such as layout, color regulation and edition, etc., on a color image displayed on a display by using an image processor.
Thereafter, the user provides a result of processing to a proof and planographic output device to cause the latter to output a proof sheet and/or a planographic sheet according to the digital data corresponding to dot-images of respective colors or digital image data corresponding to a monochromatic dot-image.
According to the disclosed system, the problems inherent to the aforementioned total printing system are solved sufficiently.
However, since the disclosed system includes various separate constitutional portions, a device necessary for constituting the system becomes large and, since electro-photographic processing time is very long, it is easily affected by attenuation of light.
Further, due to the fact that there are many portions which are in contact with an electro-photographic recording medium and precise positioning is relatively difficult, it is difficult to obtain high repeating accuracy and out of register tends to become large, which are new problems to be solved.
Further, since, in the disclosed system, a developing process is performed after about one revolution of a drum pre-processed in pre-processing liquid bath, it takes long time. The pre-processing liquid tends to be dried, causing variation of concentration.
In the disclosed system, the pre-processing is performed with a roller being dipped in pre-processing liquid in a bath. Therefore, alien such as toner floating on a level of pre-processing liquid may be adsorbed on the roller.
Further, in a wet type electro-photographic device, residual developing agent on an electro-photographic recording sheet after passed through a developing device is unavoidable. If such residual developing agent is left as it is, quality of a resultant image is degraded. In order to remove such residual developing agent on the recording sheet, the latter is passed through a residual developing agent remover comprising such as blade device, corona squeeze device or air-knife device, etc.
Among others, the air-knife device has been used since it does not considerably disorder a toner image on an image carrier surface and its construction is relatively simple.
However, efficiency of removal of residual developing agent of the conventional air-knife device is not so high as necessary for sufficient removal of residual developing agent.
When, in order to improve the efficiency of residual agent removal, air pressure is increased by increasing an amount of air to be supplied to the air-knife device, the toner image on the image carrier surface may be damaged, the developing agent may be bubbled up and/or scattered and/or evaporation of developing agent may become too much.